Device for isolating a surface for welding

ABSTRACT

A device ( 10 ) for isolating a surface for welding in an underwater location or in high fire risk areas. The device comprises a housing ( 27 ) which is arranged to be mounted on the surface and a sealing means ( 30 ) to provide a seal between the housing and the surface. The housing ( 27 ) is provided with a sealed inlet ( 50 ) for receiving a welding apparatus, a fluid inlet ( 32 ) for the passage of gas into the housing, and a fluid outlet ( 34 ) for the passage of gas and/or liquid out of the housing. A heating means FIG.  3  is not figure) for providing heated gas to the fluid inlet is also provided. In use, an ingress of heated gas through the fluid inlet ( 32 ) facilitates an egress of gas and/or liquid, contained in a space defined by the housing and the surface, through the fluid outlet ( 34 ) in the housing. In this way an in situ dry gaseous environment is provided for welding the surface. The heating means ( 100 ) is provided upstream and comprises a space with heating elements ( 120 ) surrounded by insulation ( 130 ) with electrical inlets ( 122 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a device for isolating a surfacefor welding, particularly, for example, in an underwater location or ina high fire risk area.

BACKGROUND OF THE INVENTION

[0002] The mechanical properties of a welded surface formed under “dry”welding conditions is frequently recorded to be greater than or equal to23% elongation of tensile allweld. This stands in marked contrast to themechanical properties of a welded surface which is formed under “wet”welding conditions. The elongation of tensile allweld for an underwaterwelded surface is typically about 7-8% due to rapid cooling of thewelded surface through heat dispersion to the surrounding water and ahigh concentration of hydrogen absorbed into the weld. The underwaterwelded surface is thus more brittle and weaker than a weld formed on asurface made of the same material under “dry” conditions.

[0003] It is known to provide large hyperbaric chambers which areconstructed around, so as to fully enclose, an underwater surface whichrequires welding. Such hyperbaric chambers are large enough to hold adiver and the diver's welding apparatus. In use, the hyperbaric chamberis drained of water and the diver welds the surface under “dry”conditions. The procedure is lengthy, and costly. The hyperbaricchambers are large and cumbersome to operate, and they are frequentlyoversized for the surface area which requires welding. Not surprisingly,the hyperbaric chambers are very expensive. For a very small weldedarea, the cost can run into many millions of dollars.

[0004] The present invention seeks to overcome at least some of theaforementioned disadvantages.

SUMMARY OF THE INVENTION

[0005] In accordance with a first aspect of the invention there isprovided a device for isolating a surface for welding, comprising ahousing provided with a sealed inlet for receiving a welding apparatus,a fluid inlet for the passage of gas into the housing, and a fluidoutlet for the passage of gas and/or liquid out of the housing, whereinthe housing is arranged in use to be mounted on the surface, and asealing means disposed between the housing and the surface to provide aseal between the housing and the surface, whereby, in use, an ingress ofgas through the fluid inlet in the housing facilitates an egress of gasand/or liquid, contained in a space defined by the housing and thesurface, through the fluid outlet in the housing, thereby providing anin situ gaseous environment for welding the surface.

[0006] In accordance with a second aspect of the invention there isprovided a device for isolating a surface for welding, comprising ahousing provided with a sealed inlet for receiving a welding apparatus,a fluid inlet for the passage of gas into the housing, and a fluidoutlet for the passage of gas and/or liquid out of the housing, whereinthe housing is arranged in use to be mounted on the surface, a sealingmeans disposed between the housing and the surface to provide a sealbetween the housing and the surface, and a heating means adapted toprovide heated gas to the fluid inlet of the housing wherein, in use, aningress of heated gas through the fluid inlet in the housing facilitatesan egress of gas and/or liquid, contained in a space defined by thehousing and the surface, through the fluid outlet in the housing,thereby providing an in situ dry gaseous environment for welding thesurface.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0007] The present invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which;

[0008]FIG. 1 is a side elevatory view of a device for isolating anunderwater surface from surrounding water in accordance with the presentinvention;

[0009]FIG. 2 is a plan view of the device shown in FIG. 1; and

[0010]FIG. 3 is a diagrammatic sectional view of a gas heating means foruse with the device shown in FIGS. 1 and 2.

[0011] In FIGS. 1 and 2 of the accompanying drawings there is shown adevice 10 for isolating an underwater surface from surrounding water forwelding. The device 10 includes a housing 20, a first seal 30, aflexible member 40, and a second seal 50. The housing 20 is comprised ofa plurality of upright side walls 26, a plurality of correspondinginwardly inclined upper walls 27, each upper wall 27 depending from anuppermost edge 29 of each side wall 26, and a substantially horizontaluppermost wall 25 laterally extending between uppermost edges 23 of theupper walls 27. Each side wall 26 is interconnected to an adjacent sidewall 26 along the length of its side edge 21. Similarly, each upper wall27 is interconnected to an adjacent upper wall 27 along the length ofits side edge 22. The uppermost wall 25 is provided with an aperture 42disposed in a substantially central portion of the uppermost wall 25.Thus, the housing 20 forms an open ended box-like structure.

[0012] Preferably, the housing 20 is formed from a transparent rigidplastic material, for example perspex, or constructed from stainlesssteel with polycarbonate viewing windows, or any other material havingcharacteristics for welding at depth. It is envisaged that the lengthand/or breadth of the housing will vary from about 250-300 mm to allow aweld runout length (ROL) of approximately 100-175 mm, however it iswithin the scope of the invention for the housing to have an increasedsize in proportion with the area of the surface to be welded.

[0013] The housing 20 is provided with a fluid inlet 32 and a fluidoutlet 34 disposed in opposing side walls 26. The fluid inlet 32 isadapted to be coupled with, and in fluid communication with, a gasheating means 100 as shown in FIG. 3. The fluid inlet 32 extends intothe housing 20, wherein a portion of the fluid inlet 32 disposed insidethe housing 20 is perforated, forked, or branched to allow consistentand directional flow of gas into the housing 20. It is also envisagedthat there may be a plurality of fluid inlets 32 disposed in any wall ofthe housing 20.

[0014] The first seal 30 depends from, and along the whole extent of, alowermost edge 28 of the side walls 26. Preferably, the first seal 30 ismade from a resilient plastics material, for example, neoprene orsilicone, such that the seal formed between the housing 20 and thesurface is water-tight. It is envisaged that the lowermost edge 28 ofthe side walls 26 will be provided with a contour to correspond with anexterior contour of the surface to be welded. For example, the contourof the lowermost edge 28 of the side walls 26 may be curved tocorrespond with the exterior contour of a welded pipe, or the contour ofthe lowermost edge 28 of the side walls 26 may be stepped to correspondwith the exterior contour of a stepped surface.

[0015] The flexible member 40 is comprised of a flexible tube portion 46having a first end 41 and a second end 43. The first end 41 is providedwith a flange portion 45. The flange portion 45 is arranged, in use, tobe mounted contiguously to the uppermost wall 25 of the housing 20. Inthis way, the tube portion 42 is substantially longitudinally alignedwith the aperture 42 in the uppermost wall 25.

[0016] The second end 43 of the tube portion 42 is sealed. The secondseal 50 is disposed in the second end 43 of the tube portion 42. Thesecond seal 50 is arranged in use to receive a welding apparatus, forexample a welding electrode 75 as shown in FIG. 1. Preferably the secondseal 50 is made from a resilient plastics material, for example,neoprene or silicone rubber, such that the seal formed between theelectrode 70 and the second seal 50 is water-tight.

[0017] Referring to FIG. 3, the gas heating means 100 includes a hollowheating vessel 110 having at least one gas inlet 112, a gas outlet 114,and at least one heating element 120. Preferably, the or each heatingelement 120 fixedly mounted on an inner surface 111 of the hollowheating vessel 110. Alternatively, the or each heating element 120 isdisposed substantially orthogonally in a series, to the direction of gasflow into the heating vessel 110 such that heat transfer to inflowinggas is maximised. It is envisaged that the or each heating element 120will heat an interior of the hollow heating vessel up to and around 700°C. It will be understood that the number and size of heating elements120 disposed inside the heating vessel 110 will increase in proportionto the size of the heating vessel 110.

[0018] The hollow heating vessel 110 is formed from a rigid materialwhich can withstand the degree of water pressure occurring at a depthwhere underwater welding is undertaken, and, preferably, which is alsoan efficient heat conductor. Preferably, the hollow heating vessel 110is formed from a metallic material such as stainless steel, carbonsteel, aluminium, titanium, and other suitable metallic alloys.

[0019] The hollow heating vessel 110 is provided with an insulationlayer 130, disposed contiguously on an outer surface 113 of the hollowheating vessel 110, to prevent heat dispersion from the hollow heatingvessel 110 to the surrounding water. Preferably, the insulation layer130 is formed from a synthetic plastics material, such as rubber,polyethylene, polyurethane, or any other suitable insulating material.

[0020] The or each heating element 120 is provided with a conduit 122for the supply of power to the or each respective heating element 120from an outside power source (not shown). It is envisaged that a portionof the conduit 122 is disposed in a bore of the gas inlet 112, the gasinlet 112 being provided with a water-tight seal 124 where the conduit122 enters the gas inlet 112.

[0021] The gas inlet 112 is provided with a first valve 116, the firstvalve 116 being adapted to be coupled to a welding gas source (notshown), such as a gas bottle, so as to receive gas from the welding gassource. It is envisaged that the gas will be supplied to the gas inlet112 and, subsequently, the hollow heating vessel 110 at a pressurecorresponding to a gas pressure regulated by a gas pressure regulatorlocated at the welding gas source, typically at a flow rate of 30-40litres/minute.

[0022] Typically, the temperature of the welding gas supplied to the gasinlet 112 and subsequently to the hollow heating vessel 110 is 0-25° C.The temperature of the welding gas is heated to 100-300° C., preferably130-150° C. during its residence period in the hollow heating vessel110.

[0023] The gas outlet 114 is provided with a second-valve 118, thesecond valve 118 being adapted to be coupled to the fluid inlet 32 ofthe housing 20, so as to supply heated gas to the housing 20.

[0024] In use, the housing 20 is mounted on and/or clamped to theunderwater surface which is to be welded. The first seal 30 provides awater-tight seal at the interface between the underwater surface and thelowermost edge 28 of the housing 20.

[0025] At this stage, the space defined by the surface, the housing 20and the flexible member 40 contains water. Water is expelled from thespace through the fluid outlet 34 by applying a positive pressure ofgas, for example pressurised air, diver's breathing air, nitrogen,argon, carbon dioxide, Ar/He mixture, and other suitable inert gases,through the fluid inlet 32 to effect a “dry area”. It is envisaged thatthroughout the duration of welding, the positive pressure of gas will bemaintained to ventilate the dry area, enclosed by the housing 20 ofsmoke and other fumes generated during the welding process.

[0026] If water is merely displaced from the housing 20 by gas atambient temperature, the welding environment tends to remain humidbecause of residual moisture on the welding surface. Thus, optimumconditions for conducting successful dry welds with desirable elongationof tensile allweld are not readily achieved.

[0027] The inventor has found that optimum conditions for conductingsuccessful dry welds with desirable elongation of tensile allweld can beachieved by heating the aforementioned gas to a temperature of between100-300° C., preferably 130-150° C. with the gas heating means 100 priorto the gas entering the housing 20 of the device 10, as described above.The heated gas assists in the evaporation of residual moisture on thewelding surface. In this way, the in situ environment in the vicinity ofthe underwater surface can be kept substantially dry and free of water,and the welding process can proceed under substantially similarconditions conventionally used in normal dry welding. The mechanicalproperties of a welded surface formed underwater using the presentinvention has been recorded to be 23-26% elongation of tensile allweld.

[0028] The welding electrode 75 is introduced into the housing 20 bypiercing the second seal 50 with the welding electrode 75, and thenfeeding the welding electrode 75 through the flexible tube portion 46and the aperture 42 in the uppermost wall 25 of the housing 20. Thewelding electrode 75 is held in a desired position and manipulated withan electrode holder. The flexible nature of the flexible tube portion 46allows an operator to move and manipulate the welding electrode 75within the housing 20. The transparent character of the housing 20allows the operator to view the welding process as it proceeds.

[0029] When the operator has completed a weld run, the housing 20 can beremoved from the underwater surface and repositioned to allow the nextweld run to be completed. After the weld run is fully completed thehousing 20 can be repositioned on the next weld joint.

[0030] It is envisaged that the device 10 will be suitable for a widevariety of welding processes and applications required for underwatersurfaces including manual metal-arc welding, gas-metal arc welding, andflux core welding performed on off-shore structures, oil rigs andplatforms, hull section repair, pipeline etc.

[0031] The purpose of the present invention is to provide an efficientand cost-effective means by which wet underwater surfaces may be weldedunderwater under “dry” conditions.

[0032] It is also envisaged that the present invention will beparticularly suitable for use in a dry environment where it is desirableto isolate a welding area in a confined area to prevent dispersion ofsparks in a toxic/explosive/flammable environment. The present inventionis also suitable for use in a hyperbaric environment where it isdesirable to create a good welding environment which is not hydrogenrich and has low humidity. Modifications and variations as would beapparent to a skilled addressee are deemed to be within the scope of thepresent invention.

1. A device for isolating a surface for welding, comprising a housing provided with: a sealed inlet for receiving a welding apparatus, wherein the sealed inlet is disposed in a flexible member to allow the welding apparatus to be manipulated within the housing; a fluid inlet for the passage of heated gas into the housing, and a fluid outlet for the passage of heated gas and/or liquid out of the housing; and a transparent viewing portion, mounted on the surface wherein the housing is arranged in use to be, and a sealing means disposed between the housing and the surface to provide a seal between the housing and the surface, whereby, in use, an ingress of heated gas through the fluid inlet in the housing facilitates an egress of gas and/or liquid contained in a space defined by the housing and the surface through the fluid outlet in the housing, thereby providing an in situ substantially dry, gaseous environment for welding the surface.
 2. The device according to claim 1, characterised in that the device further comprises a heating means adapted to provide heated gas to the fluid inlet of the housing.
 3. The device according to claim 2, characterised in that the heating means comprises a vessel having at least one gas inlet, a gas outlet, and at least one heating element.
 4. The device according to claim 3, characterised in that the heating element is mounted on an inner surface of the vessel.
 5. The device according to claim 3 characterised in that the or each heating element is disposed substantially orthogonally to the direction of gas flow into the heating vessel.
 6. The device according to any one of claims 3 to 5, characterised in that the or each heating element heats an interior of the vessel up to and around 700° C.
 7. The device according to any of claims 3 to 6, characterised in that the vessel is formed from a rigid material which can withstand a degree of water pressure occurring at a depth where underwater welding is undertaken.
 8. The device according to claim 7, characterised in that the rigid material is an efficient heat conductor.
 9. The device according to claim 7 or claim 8, characterised in that the vessel is formed from a metallic material selected from a group comprising stainless steel, carbon steel, aluminium, titanium, metallic alloys.
 10. The device according to any one of claims 3 to 9, characterised in that the vessel is provided with an insulation layer disposed contiguously on an outer surface of the vessel.
 11. The device according to claim 10, characterised in that the insulation layer is formed from a synthetic plastics material.
 12. The device according to any one of claims 3 to 11, characterised in that the or each heating element is provided with a conduit for the supply of power to the or each respective heating element from a power source.
 13. The device according to any one of claims 3 to 12, characterised in that the gas inlet is provided with a first valve, the first valve being adapted to be coupled to a welding gas source, so as to receive gas into the vessel.
 14. The device according to any one of claims 3 to 13, characterised in that the gas outlet is provided with a second valve, the second valve being adapted to be coupled to the fluid inlet of the housing, so as to supply heated gas to the housing.
 15. The device according to any one of claims 3 to 14, characterised in that the or each heating element is arranged to heat gas received in the vessel to 100-300° C. during a residence period of the gas in the vessel.
 16. The device according to claim 15, characterised in that the gas is heated to 130-150° C. during the residence period in the vessel.
 17. The device according to any one of claims 1 to 16, characterised in that the fluid inlet and the fluid outlet are disposed in opposing walls of the housing.
 18. The device according to any one of claims 1 to 17, characterised in that a portion of the fluid inlet extends into the housing.
 19. The device according to claim 18, characterised in that the portion is perforated, forked, or branched.
 20. The device according to any one of claims 1 to 19, characterised in that there is more than one fluid inlet disposed in the housing.
 21. A device according to any one of claims 2 to claim 20, characterised in that the fluid inlet is adapted to be coupled with, and in fluid communication with the heating means.
 22. The device, according to any one of claims 1 to 21, characterised in that the sealing means depends from, and along the whole extent of, a lowermost edge of the housing.
 23. The device according to anyone of claims 1 to 22, characterised in that the sealing means is formed from a resilient plastics material.
 24. The device according to any one of the claims 1 to 23, characterised in that the sealing means is formed from a material wherein the seal formed between the housing and the surface is water-tight.
 25. The device according to any one of claims 1 to 24, characterised in that the lowermost edge of the housing is provided with a contour to substantially correspond with an exterior contour of the surface.
 26. The device according to any one of claims 1 to 25, characterised in that the housing is formed from a transparent rigid plastics material.
 27. The device according to any one of claims 1 to 26, characterised in that the housing is formed from stainless steel with polycarbonate viewing windows.
 28. The device according to any one of claims 1 to 27, characterised in that the flexible member is comprised of a flexible tube portion mounted contiguously to an uppermost wall of the housing, wherein the tube portion is substantially longitudinally aligned with an aperture in the uppermost wall. 